Influence of Divalent Cations on Nucleotide Exchange and ATPase Activity of Chloroplast Coupling Factor 1†

Biochemistry ◽  
1998 ◽  
Vol 37 (49) ◽  
pp. 17209-17215 ◽  
Author(s):  
Jeanne G. Digel ◽  
Nakisha D. Moore ◽  
Richard E. McCarty
Keyword(s):  
Atpase Activity ◽  
Divalent Cations ◽  
Coupling Factor ◽  
Nucleotide Exchange ◽  
Chloroplast Coupling Factor ◽  
Chloroplast Coupling Factor 1

Energy Transfer Inhibition Induced by Nitrofen

1982 ◽  
Vol 37 (9) ◽  
pp. 787-792 ◽  
Author(s):  
Bernhard Huchzermeyer
Keyword(s):  
Energy Transfer ◽  
Atpase Activity ◽  
Enzymatic Activity ◽  
Strong Correlation ◽  
Coupling Factor ◽  
Regulatory Effect ◽  
Nucleotide Exchange ◽  
Chloroplast Coupling Factor ◽  
Transfer Inhibitor ◽  
Transfer Inhibition

The herbicide nitrofen was shown to act as an energy transfer inhibitor. The results proved nitrofen to act by inhibiting nucleotide exchange on the chloroplast coupling factor. A strong correlation was found between the inhibition of phosphorylation, ATPase activity, and nucleotide exchange. These results are discussed in terms of a regulatory effect of tightly bound ADP on the enzymatic activity of the chloroplast coupling factor.

A Fluorescence Method for Measuring the Retention of Coupling Factor (CF1) in Reconstitution Experiments of Photophosphorylation

1977 ◽  
Vol 32 (5-6) ◽  
pp. 392-397 ◽  
Author(s):  
Götz Harnischfeger ◽  
Reinhard Schopf
Keyword(s):  
Atpase Activity ◽  
Thylakoid Membranes ◽  
Coupling Factor ◽  
Fluorescence Method ◽  
Double Labeling ◽  
Atp Formation ◽  
Chloroplast Coupling Factor ◽  
Chloroplast Coupling Factor 1 ◽  
Covalently Bound

Abstract The recombination of chloroplast coupling factor 1 (CF1) and thylakoid membranes in reconsti­ tution experiments was studied through the fluorescence of paired labels covalently bound to NH2-groups. It was found that maximum recombination is achieved at a ratio of 1.5 -3,μg CF1 /μg chlorophyll. The addition of chloroplast lipids to the medium enhances the incorporation of CF1 into the membranes. The rates of ATP formation of the regenerated but labeled system are decreased to 50% of those found in unlabeled control experiments. This is discussed in context with the previous observation, that labeling of CF1 at similar concentrations inhibits the ATPase activity of the isolated protein completely. The possible use of double labeling in the study of the physical aspects of the reconstitution of the photophosphorylating system is discussed.

Studies on the Retention of CF1 with or without Induced ATPase Activity by Pyrophosphate Treated Thylakoids and Its Relation to the Regeneration of Photophosphorylation

1977 ◽  
Vol 32 (5-6) ◽  
pp. 398-404 ◽  
Author(s):  
R. Schopf ◽  
G. Harnischfeger
Keyword(s):  
Atpase Activity ◽  
Differential Effect ◽  
Atp Synthesis ◽  
Thylakoid Membranes ◽  
Coupling Factor ◽  
Trypsin Treatment ◽  
Atp Formation ◽  
Chloroplast Coupling Factor ◽  
Reconstitution Experiment ◽  
Chloroplast Coupling Factor 1

Abstract The reconstitution of chloroplast coupling factor 1 (CF1) into thylakoid membranes was investigated by the fluorescence of the covalently attached label fluorescamine. In contrast to a func­tional regeneration of ATP synthesis, a rebinding of CF1 was observed regardless if the protein was in its native, purified state or had been activated for ATPase activity by heat, dithiothreitol (DTT) or trypsin treatment. The reintegration of CF1 into the thylakoid membrane was estimated to be almost quantitative. Since the label binds covalently and irreversibly to free NH2-groups, its effects on the various functional parameters were investigated. Blocking of NH2 groups leads to inhibition of ATPase activity in isolated CF1 . Labeled factor used in a reconstitution experiment on the other hand, does still result in considerable regeneration of ATP formation. Attaching the label to whole thylakoids leads to a differential effect on phosphorylation, which is inhibited, and the H+-uptake which seems largely unaffected. A differential effect is also observed on coupled and uncoupled electron transport. The results are interpreted as evidence for an involvement of free NH2-groups in the mechanism of photophosphorylation.

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